1
Determining the absorption tolerance of single chromophore photodiodes for machine
vision
R. Jansen van Vuuren1, K. D. Johnstone1, S. Ratnasingam3, H. Barcena1, P. C. Deakin2, A. K.
Pandey4, P. L. Burn1, S. Collins3, and I. D. W. Samuel4
1
Centre for Organic Photonics & Electronics, The University of Queensland, 4072
Queensland, Australia
2
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield
Rd, OX1 3TA Oxford, UK
3
Department of Engineering, University of Oxford, Parks Rd, OX1 3PJ Oxford, UK
4
Organic Semiconductor Centre, School of Physics & Astronomy, SUPA, University of St
Andrews, North Haugh, KY16 9SS Fife, UK
Supplementary Information
Simulation Details
The effect on feature F1 and F2 of a variety of phenomena including temporal noise, the
effects of an analogue to digital converter and sensors that respond over a range of
wavelengths, and the fact that the spectrum of daylight is not described by Wein’s
approximation have been studied numerically1. The reflectance data of Munsell colors and
the daylight spectra used in these studies were sampled at 1 nm intervals. The simulated
response of each sensor to a reflectance under different illumination conditions was obtained
by integrating the product of the particular Munsell reflectance, the CIE standard daylight
spectra and a function or data representing the spectral sensitivity of the sensors. To represent
the effects of temporal noise the result of the integral was then multiplied by a normal
distribution with a mean value of one and standard deviation of 0.01. The final step in the
simulation was then to represent the effects of using an analogue to digital converter (ADC)
to convert the sensor responses to digital quantities. In representing the quantiser effect the
first stage is to determine the maximum sensor response. A white standard reflectance and
the CIE standard daylight illuminant (6500 K) was used to determine this maximum
response. This maximum sensor response was then divided by 210, to represent a 10 bit ADC.
A typical feature space obtained using 14 CIE standard daylights and 202 Munsell
reflectances with similar relative brightness is shown in Figure S1. In this figure each cross
2
represents the actual color of the Munsell reflectance when illuminating with one of the 14
CIE daylight spectra. This figure shows that as required most different colors are widely
separated in the space and most similar colors are near neighbours. A closer inspection of the
feature space shows that noise and a residual dependence on the spectrum of the illuminating
light means that each of the Munsell reflectances creates a small cluster of responses in the
feature space. The size of these clusters depends upon several factors including the width of
the sensor responses, the amount of noise in the sensor responses and the difference between
the spectrum of the light source and that of a blackbody. To determine the width of the sensor
responses needed to obtain useful features a method has been proposed to determine the
significance of the area occupied by each cluster1.
0.6
0.5
0.4
F2
0.3
0.2
0.1
0
-0.1
-0.2
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
F1
Figure S1: The two dimensional feature space formed with 80 nm FWHM equal weight
sensors when applying 202 Munsell surfaces and 14 CIE standard daylights. Each cross is the
color of the relevant Munsell color. In this case the sensor responses were represented using
10 bits.
The cluster of points formed by each of the Munsell reflectances when illuminating with CIE
standard test daylights form a non-uniform distribution of points (see Figure S2). To account
for this observed non-uniform distribution it is appropriate to use a distance metric which
takes this non-uniform nature of cluster points into account. Therefore, the Mahalanobis
distance was applied to determine a boundary that ideally encloses all points in each cluster
of responses corresponding to the same Munsell reflectance. For n-dimensional normally
distributed data, the Mahalanobis distance between the centre of the cluster C and a data point
P is defined as:
3
DM2  ( P  C )'  1 ( P  C )
where Σ is the covariance matrix of the distribution. For a pair of surface reflectances
representing colors separated by a known distance in CIELab space the Mahalanobis distance
can be used to determine a boundary around each cluster. To determine the Mahalanobis
distance boundary of a particular reflectance pair the first step is to find the centre of each
cluster of responses. Then the Mahalanobis distance from the centre of the respective clusters
to the boundary was increased from a small value until the boundaries formed by both
members of a pair touch each other. To assess the dependency of the feature space on the
illuminant, the number of responses that fall inside the correct boundary in the pair was then
counted.
0.24
0.22
0.2
F
2
0.18
0.16
0.14
0.12
0.1
0.2
0.25
F
0.3
0.35
1
Figure S2: The clusters of points formed by Munsell reflectances corresponding to colors that
are good matches to each other. In this figure the colors have been chosen to allow the four
constituent parts of the figure to be seen easily and have no significance. In particular the
blue and red crosses are the features extracted from noisy responses to each of the two
reflectances under different illuminants. The purple and the green are then the boundaries
drawn around each of the clusters so that the boundaries just touch.
To assess the quality of the information that can be obtained from F1 and F2 the pairs of
reflectances that are separated by six units in CIELab space have been used. In addition to
being independent of the spectrum of the illuminant F1 and F2 are also independent of the
brightness of the illuminant. This means that they are also independent of the lightness of any
color and are therefore related to the chromaticity of the color. To assess the feature space
reflectances that differ only by chromaticity have been obtained by scaling the 1269 Munsell
reflectance spectra so that all these scaled spectra have a luminance component in CIELab
4
color space of 50 units. This particular value of the L component of CIELab was chosen
because it is the middle of the range and possible L values and it is also used in defining the
CIE standard color difference model (E94)2. Critically this scaling means that pairs of
reflectance spectra can be selected that only differ by their chromaticity. From this
normalised Munsell data a set of 100 pairs of reflectances that differ by between 5.995 to
6.005 CIELab units were chosen randomly. To assess the dependency of the feature space on
the illuminator the number of responses that fall inside the correct boundary in the pair was
then counted. This test was performed on all the 100 pairs of reflectances in the test data set
and the percentage of points falling within the boundary was recorded.
Experimental Details
All solvents were distilled prior to use. N,N-Dimethylformamide was dried over calcium
hydride, filtered, and distilled under reduced pressure. Tetrahydrofuran was freshly distilled
over sodium and benzophenone. Column chromatography was performed with Kieselgel 60
230-400 mesh silica purchased from Merck (cat. number 1.09385.9025). 1H and
13
C NMR
spectroscopy was performed on Bruker Avance AV-300, AV-400 or AV-500 MHz
spectrometers: spH = surface phenyl H; bpH = branch phenyl H; IndH = indolenyl H; ThH =
thiophenyl H; cpH = cyclopentanone H. Coupling constants are given to the nearest 0.5 Hz
and br = broad. UV-visible spectroscopy were performed on a Cary 5000 UV-Vis
spectrophotometer as either a thin film on quartz or as a solution in spectroscopic grade
solvent (sh = shoulder). FT-IR spectroscopy was performed on solid samples using a PerkinElmer Spectrum 100 FT-IR Spectrometer with ATR attachment. Melting points were
determined using a Buchi B-545 melting point apparatus. Differential scanning calorimetry
was performed with a Perkin-Elmer Diamond DSC. Microanalyses were performed on a
Carlo Erba NA 1500 Elemental Analyser. Matrix-assisted laser-desorption ionisation time of
flight (MALDI-TOF) mass spectrometry was performed on a Voyager DE STR MALDI-TOF
spectrometer. Electrospray ionisation mass spectrometry was performed on a BRUKER HCT
3D Ion Trap mass spectrometer. Quartz substrates were cleaned by sonication at 80 °C with
Alconox detergent (1g/100 mL in MilliQ water), then scrubbed using Kim-wipes before
being sequentially sonicated at 50 °C in Alconox (1 g/100 mL in MilliQ water), MilliQ water,
acetone, and 2-propanol. The substrates were dried under a stream of nitrogen immediately
prior to spin-coating. Compounds were spin coated onto 2.5 cm x 2.5 cm square pre-cleaned
quartz substrates using a Cookson Electronics G3-8 speciality coating system. Film
thicknesses were determined using a Dektak 150 Profilometer.
5
5,5'''-Bis{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-[2,2':5',2":5'',2''']-quaterthiophene
(1)
5-Bromo-5'-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-[2,2’]-bithiophene3 (119 mg, 0.16
mmol), bis(pinacolato)diboron (41.4 mg, 0.16 mmol), potassium acetate (50 mg, 3 equiv.),
and N,N-dimethylformamide (5 mL) were placed in a pressure tube. The mixture was freezepump-thaw
degassed
three
times,
then
back-filled
with
nitrogen.
Bis(triphenylphosphine)palladium(II) dichloride (6 mg, 8.2 μmol) was added under nitrogen
and the mixture was freeze-pump-thaw degassed twice, then back-filled with nitrogen. The
reaction mixture was stirred at 75 °C overnight. The reaction was allowed to cool to room
temperature before being diluted with toluene (50 mL). The solution was washed with a
saturated aqueous solution of sodium hydrogen carbonate (2 x 25 mL) and brine (30 mL),
dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The residue was
purified using column chromatography over silica using dichloromethane:hexane mixtures
(0:100 to 1:4) to yield 1 (63 mg, 30%) as a red-orange amorphous solid. Tg: 31 °C; Solution
UV-vis (CH2Cl2): λmax(ε) 269 nm (4.1 x 105), 431 nm (2.9 x 105); Thin Film UV-vis (10
mg/mL spin-coated: toluene, 1500 rpm, 120 sec; film thickness = 30 nm): λmax 438 nm; 1H
NMR (300 MHz, CDCl3) δ 0.91-0.99 (24 H, m, CH3), 1.32-1.63 (32 H, m, CH2), 1.78 (4 H,
m, CH), 3.91 (8 H, m, ArOCH2), 7.02 and 7.60 (16 H, AA’BB’, spH), 7.10 (2 H, d, J = 4.0,
ThH), 7.14 (2 H, d, J = 4.0, ThH), 7.18 (2 H, d, J = 4.0, ThH), 7.33 (2 H, d, J = 4.0, ThH),
7.64 (2 H, dd, J = 1.5, J = 1.5, bpH), 7.69 (4 H, d, J = 1.5, bpH);
13
C NMR (100 MHz,
CDCl3) δ 11.1, 14.1, 23.1, 23.9, 29.1, 30.5, 39.4, 70.6, 114.9, 122.4, 124.1, 124.3, 124.4,
124.6, 124.8, 128.2, 133.0, 134.7, 135.9, 136.36, 136.41, 142.2, 143.4, 159.3; MS (MALDITOF, m/z, dithranol) 1299.1 (100%) [M] +, Anal. Calcd for C84H98O4S4: C, 77.6; H, 7.6; S
9.9. Found: C, 77.5; H, 7.6; S 9.5.
5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole
A
mixture
of
2-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane4 (1.84 g, 3.01 mmol), 5-bromo-2,3,3-trimethyl-3H-indole5 (594 mg, 2.50
mmol), tetrakis(triphenylphosphine)palladium(0) (145 mg, 0.126 mmol), aqueous sodium
carbonate (2 M, 7.0 ml), ethanol (10 mL) and toluene (18 mL) was deoxygenated by vacuumnitrogen purging three times and then heated at reflux for 45 h. The mixture was allowed to
cool and water (60 mL) and ether (60 mL) were added. The organic layer was removed and
the aqueous layer was extracted with ether (2 x 100 mL). The organic layer and the ether
extracts were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent
6
removed. The residue was purified by column chromatography over silica using ethyl
acetate:light petroleum mixtures (1:4 to 1:1) as eluent to give 5-{3,5-bis[4-(2ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole (1.55 g, 97%) as a viscous yellow
oil. UV-vis (THF): λmax(ε) 276 (1.8 x 105); 1H NMR (400 MHz, CDCl3) δ 0.90-0.97 (12 H,
m, CH3), 1.32-1.60 (22 H, m, CH2 & C(CH3)2), 1.72-1.82 (2 H, m, CH), 2.34 (3 H, s, NCH3), 3.91 (4 H, d, ArOCH2), 7.02 (4 H, 1/2AA’BB’, spH), 7.57 (1 H, m, IndH), 7.61-7.65
(6 H, m, spH & IndH), 7.69 (3 H, s, bpH); 13C NMR (100 MHz, CDCl3) δ 11.1, 14.1, 15.5,
23.1, 23.2, 23.9, 29.1, 30.5, 39.4, 53.8, 70.6, 114.9, 119.9, 120.5, 124.2, 127.0, 128.3, 133.5,
138.8, 142.0, 142.4, 146.2, 152.8, 159.18, 159.24, 188.6; MS (ESI+, m/z, DCM) 644.6
(100%) [MH]+; Anal. Calcd for C45H57NO2: C, 83.9; H, 8.9; N, 2.2. Found: C, 83.9; H, 9.1;
N, 2.2.
5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indolium iodide
A mixture of 5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indole (0.73
g, 1.1 mmol) and methyl iodide (0.8 mL, 12.8 mmol) in acetonitrile (2 mL) and
tetrahydrofuran (2 mL) was deoxygenated by vacuum-nitrogen purging three times and then
heated at reflux in the dark for 36 h. The mixture was then allowed to cool before the
volatiles were removed in vacuo. Light petroleum (40 mL) was then added and the mixture
stirred under ambient conditions in the dark for 45 min. The solvent was decanted and the
residue dried, providing the product as dark green crystals (891 mg, quantitative). m.p. 116118 °C; UV-vis (THF): λmax(ε) 276 (6.2 x 105); 1H NMR (300 MHz, CDCl3) δ 0.89-0.98 (12
H, m, CH3), 1.30-1.59 (16 H, m, CH2), 1.73-1.81 (8 H, m, CH & C(CH3)2), 3.15 (3 H, s, NCH3), 3.90 (4 H, m, ArOCH2), 4.34 (3 H, s, -NCH3), 7.02 (4 H, 1/2AA’BB’, spH), 7.587.64 (6 H, spH & bpH), 7.73-7.77 (3 H, m, bpH & IndH), 7.86 (1 H, dd, J = 8, J = 1.5,
IndH);
13
C NMR (100 MHz, CDCl3) δ 11.1, 14.1, 17.0, 23.0, 23.3, 23.9, 29.1, 30.5, 37.3,
39.4, 54.7, 70.6, 115.0, 115.4, 122.0, 124.3, 125.5, 128.3, 128.7, 132.8, 140.2, 141.1, 142.0,
142.5, 144.2, 159.4, 195.6; MS (ESI+, m/z, 5% DCM/MeOH) 658.4 (100%) [M+], 784.2
(18%) [MI]+; Anal. Calcd for C46H60INO2: C, 70.3; H, 7.7; N, 1.8. Found: C,70.3; H, 7.8; N,
1.8.
5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indol-2-ylideneacetaldehyde
5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indolium iodide (184 mg,
0.23 mmol) and potassium t-butoxide (80 mg, 0.71 mmol) were dissolved in tetrahydrofuran
7
(5 mL) and stirred under nitrogen at ambient temperature for 2 h. The solvent was removed
before water (50 mL) and ether (50 mL) were added. The organic layer was removed and the
aqueous layer was extracted with ether (2 x 50 mL). The organic layer and the ether extracts
were combined, dried over anhydrous magnesium sulfate, filtered, and the solvent removed
to afford the enamine intermediate, which was used immediately without purification.
Phosphorous oxychloride (0.3 mL, 3.2 mmol) was added dropwise with stirring to dry N,N,dimethylformamide (0.4 mL) holding the temperature <10 °C under anhydrous conditions. A
solution of the enamine in dry N,N,-dimethylformamide (0.2 mL) was then added to the
mixture at this temperature, and the reaction was then heated at 35 °C for 45 min. Ice water
(20 mL) was then added to the reaction mixture followed by a saturated aqueous sodium
hydroxide solution (5 mL) until the pH of the mixture was approximately 10. The reaction
mixture was then heated at reflux for 20 min. The mixture was allowed to cool before brine
(30 mL) and ether (30 mL) were added. The organic layer was removed and the aqueous
layer was extracted with ether (2 x 30 mL). The organic layer and the ether extracts were
combined, dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The
crude product was purified using column chromatography over silica using ethyl acetate:light
petroleum mixtures (1:19 to 1:1) as eluent to give the product as a pink amorphous solid (119
mg, 75%). m.p. 64-66 °C; UV-vis (THF): λmax(ε) 232 (4.7 x 104) 274 (4.7 x 104), 347 (4.2 x
104); FT-IR (solid) υ = 1634 (C=O) cm-1; 1H NMR (400 MHz, CDCl3) δ 0.90-0.98 (12 H, m,
CH3), 1.31-1.60 (16 H, m, CH2), 1.72-1.82 (8 H, m, CH & C(CH3)2), 3.34 (3 H, s, -NCH3),
3.91 (4 H, m, ArOCH2), 5.50 (1 H, d, J = 9.0, vinylH), 6.97 (1 H, d, J = 8.0, IndH), 7.02 (4 H,
1/2AA’BB’, spH), 7.54 (1 H, d, J = 1.5, IndH), 7.60-7.64 (5 H, m, spH & IndH), 7.64 (2 H,
d, J = 2.0, bpH), 7.69 (1 H, dd, J = 2.0, J = 2.0, bpH), 9.95 (1 H, d, J = 9.0 Hz); 13C NMR
(100 MHz, CDCl3) δ 11.3, 14.2, 23.2, 24.0, 29.2, 29.8, 29.9, 30.7, 39.5, 47.7, 70.8, 99.5,
108.3, 115.0, 121.1, 124.0, 124.4, 127.4, 128.4, 133.5, 136.3, 140.3, 141.9, 142.3, 143.2,
159.4, 173.7, 186.7; MS (ESI+, m/z, MeOH) 686.0 (100%) [M+]; Anal. Calcd for C47H59NO3:
C, 82.3; H, 8.7; N, 2.0. Found: C, 82.1; H, 8.8; N, 2.1.
2,5-Bis[2-(1,3,3-trimethyl-5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}indolin-2ylidene)ethylidene]cyclopentanone (2)
A solution of 5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-2,3,3-trimethyl-3H-indol-2ylidene-acetaldehyde (284 mg, 0.41 mmol) and potassium t-butoxide (60 mg, 0.53 mmol) in
dry tert-butanol (4.2 mL) was heated at reflux for 30 min. Cyclopentanone (20 L, 0.23
8
mmol) was added dropwise to the solution and the reaction mixture was stirred at reflux for
18 h before being cooled to room temperature and the solvent removed. The residue was
purified by column chromatography over silica using ethyl acetate:hexanes mixtures (1:9 to
1:3) as eluent to give 2 (48 mg, 16%) as a gold/purple solid. Tg 98 °C; UV-vis (THF): λmax(ε)
272 (1.4 x 105), 340 (sh; 3.7 x 104), 356 (sh;2.81 x 104), 410 (sh;2.0 x 104), 439 (sh;1.7 x 104)
480 (sh; 5.6 x 104), 516 (9.1 x 104); Thin Film UV-vis (27 mg/mL, spin-coated:
chlorobenzene, 2000 rpm, 60 secs; film thickness = 85 nm): λmax 529 nm; FT-IR (solid) υ =
1559 (C=O) cm-1; 1H NMR (400 MHz, CDCl3) 0.90-0.97 (24 H, m, CH3), 1.32-1.62 (16 H,
m, CH2), 1.72-1.81 (32 H, m, CH & C(CH3)2), 2.77 (4 H, s, cpH), 3.27 (6 H, s, -NCH3),
3.91 (8 H, m, ArOCH2), 5.36 (2 H, d, J = 13.0, vinylH), 6.79 (2 H, br d, J = 8.0, IndH), 7.01
and 7.61 (16 H, AA’BB’, spH), 7.50 (2 H, br s, IndH), 7.54 (2 H, dd, J = 8.0, J = 1.5, IndH),
7.65 (6 H, bs, bpH), 7.76 (2 H, br d, J = 13, vinylH); MS (MALDI-TOF, m/z, dithranol)
1420.2 (100%) [M]+.
1,3,3-Trimethyl-5-[3,5-bis(4-tert-butylphenyl)phenyl]-2-(3-{1,3,3-trimethyl-5-[3,5-bis(4tert-butylphenyl)phenyl]indolin-2-ylidene}prop-1-enyl)-3H-indolium iodide (3)6
Thin Film UV-vis (20 mg/mL, spin-coated: chloroform, 1000 rpm, 60 secs; film thickness =
110 nm): λmax 590 nm.
4-[(5-Bromo-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-bromo-1,3,3trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate
1-Butanol (40 mL) and toluene (40 mL) was added to 5-bromo-1,3,3-trimethyl-3H-indolium
iodide7 (1.50 g, 3.95 mmol) and squaric acid (214 mg, 1.88 mmol). Quinoline (0.468 mL,
3.95 mmol) was added, and the reaction mixture was heated at reflux with a Dean-Stark
apparatus for at least 10 h. The solvents were removed and the residue was dissolved in
chloroform (400 mL). The organic layer was washed with aqueous hydrochloric acid (3 M, 5
x 75 mL) and brine (75 ml) before being dried with anhydrous magnesium sulphate, filtering
and removing the solvent to give a dark blue solid of 4-[(5-bromo-1,3,3-trimethyl-3Hindolium-2-yl)methylene]-2-[(5-bromo-1,3,3-trimethylindolin-2-ylidene)methyl]-3oxocyclobut-1-enolate (1.05 g, 96%). m.p. 367-368 °C; UV-vis (CHCl3): λmax(ε) 269 (1.3 x
104), 283 (sh; 1.2 x 104), 348 (sh; 5.3 x 103), 590 (sh; 3.6 x 104), 641 (2.5 x 105); FT-IR υ =
1595 (C=O) cm-1; 1H NMR (300 MHz, CDCl3) δ 1.77 (12 H, broad s, CH3), 3.54 (6H, br s,
NCH3), 5.92 (2 H, br s, vinylH), 6.87 (2 H, d, J = 9.0, IndH), 7.42-7.44 (4 H, m, IndH); MS
9
(MALDI-TOF, m/z, dithranol) 582.51 (100%) [MH]+; Anal. Calcd for C28H26Br2N2O2: C,
57.75; H, 4.5; N, 4.8. Found: C, 57.5; H, 4.45; N, 4.7.
4-[(5-{3,5-Bis[4-(2-ethylhexyloxy)phenyl]phenyl}-1,3,3-trimethyl-3H-indolium-2yl)methylene]-2-[(5-{3,5-bis[4-(2-ethylhexyloxy)phenyl]phenyl}-1,3,3-trimethylindolin-2ylidene)methyl]-3-oxocyclobut-1-enolate (4)
A mixture of 4-[(5-bromo-1,3,3-trimethyl-3H-indolium-2-yl)methylene]-2-[(5-bromo-1,3,3trimethylindolin-2-ylidene)methyl]-3-oxocyclobut-1-enolate (329 mg, 0.620 mmol), 3,5bis[4-(2-ethylhexyloxy)phenyl)]phenylboronic acid8 (176 mg, 0.302 mmol), sodium
carbonate (65.7 mg, 0.62 mmol), and tetrakis(triphenylphosphine)palladium(0) (17.5 mg, 15
mol) was degassed and backfilled with argon. Deoxygenated toluene (2 mL), water (330
L), and ethanol (330 L) were added, and then the reaction mixture was heated at reflux for
at least 10 h. Chloroform (30 mL) was added and the mixture was washed with brine (30
mL). The organic layer was dried over anhydrous magnesium sulfate, filtered, and the solvent
removed. The residue was purified by column chromatography over silica using
chloroform:acetone mixtures (1:0 to 95:5) as eluent to give 4 as a dark blue solid (355 mg,
84%), m.p. 281-285 °C; UV-vis (CHCl3): λmax(ε) 271 (1.8 x 105), 334 (sh; 2.6 x 104), 367
(sh; 1.4 x 104), 608 (sh; 9.8 x 104), 658 (5.4 x 105); Thin Film UV-vis (5 mg/mL, spin-coated:
chloroform, 3000 rpm, 60 secs film thickness = 40 nm): λmax 675 nm; FT-IR (solid) υ = 1599
(C=O) cm-1; 1H NMR (300 MHz, CDCl3) δ 0.91-0.99 (24 H, m, CH3), 1.22-1.60 (32 H, m,
CH2), 1.72-1.94 (16 H, m and br s, CH & C(CH3)2), 3.63 (6 H, br s, NCH3), 3.92 (8 H, m,
ArOCH2), 5.99 (2 H, br s, vinylH), 7.04 (8 H, 1/2AA’BB’, spH), 7.10 (2 H, d, J =9, IndH),
7.61-7.72 (18 H, m, bpH, spH, & IndH); MS (MALDI-TOF, m/z, dithranol matrix) 1393.2
(100%) [M]+; Anal. Calcd for C96H116N2O6: C, 82.7; H, 8.4; N, 2.0. Found: C, 82.6; H, 8.6;
N, 2.0.
References
1
S. Ratnasingham and S. Collins, J. Opt. Soc. Am. A 27 (2), 286-294 (2010).
2
H. C. Lee, Introduction to Color Imaging Science, Cambridge University Press, (2005).
3
E. J. Wren, K. Mutkins, M. Aljada, P. L. Burn, P. Meredith, G. Vamvounis, submitted.
4
S.C. Lo, E.B. Namdas, P.L. Burn and I.D.W. Samuel, Macromolecules 36 (26), 9721-9730
(2003).
5
M.V. Reddington, Bioconjugate Chemistry 18 (6), 2178-2190 (2007).
10
6
A. K. Pandey, P. C. Deakin, R. Jansen Van Vuuren, P. L. Burn, I. D.W. Samuel, Adv.
Mater., 2010, in press.
7
The indolium salt was prepared by the conventional reaction of the corresponding 2,3,3trimethylindolinine derivatives with methyl iodide. See S. Yagi, K. Maeda, H. Nakazumi, J.
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8
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